blocking twitter / X from app

[Puett2012]

Hi, I could block twitter on my fritz box router to avoid that my sons enters the internet on his amazon fire tablet via spotify ("Einstellungen" (settings), "Abo kündigen (cancel sbuscription (?), scrolling down on internal website and pressing the twitter bird (quite clever, my boy). Since twitter became X, it doesn't work anymore. Can anyone help? Thanks, Jens